At least five key staff members have left the Khmer Rouge tribunal’s investigating judges’ office since April, but the judges said Sunday they currently have enough staff to perform court functions.

Investigating judges Siefried Blunk and You Bunleng said in a statement Sunday they would work with remaining staff and “short-term contractors” as the UN-backed court moves forward.

But court observers say the exodus signals trouble within that office, which has come under increased scrutiny since it abruptly ended investigation into a controversial case.

Four legal assistants and a legal consultant have left since the April 29 “conclusion” announcement for Case 003, which marked an important procedural step in the investigation of two senior Khmer Rouge cadre so far unnamed by the court.

The Cambodia Daily reported Monday that Stephen Heder, a historian and consultant for the court, had left May 5 thanks in part to the judges’ decision to halt the investigation.

“In view of the judges’ decision to close the investigation into case file 003, effectively without investigating it, which I, like others, believe was unreasonable; in view of the UN staff’s evidently growing lack of confidence in your leadership, which I share; and in view of the toxic atmosphere of mutual mistrust generated b y your management of what is now a professionally dysfunctional office, I have concluded that no good use can or will be made of my consultancy services,” Heder was quoted as writing to Blunk in a resignation e-mail.

Blunk and You Bunleng have been engaged in a bitter, public debate with UN prosecutor Andrew Cayley over the investigation, which the prosecutor says was inadequate.

The two judges said Sunday they welcomed the departure of the staff, and they downplayed speculation the resignations had to do with a protest over their handling of Case 003, which Prime Minister Hun Sen and other officials oppose.

However, longtime observers of the court said the statement signaled more trouble ahead.

“For any reason, the desertion explains an inacceptable process within the court,” said Chhang Youk, director of the Documentation Center of Cambodia, which researches Khmer Rouge atrocities.